Characteristics of air-showers and accompanied high energy atmospheric families detected in the hybrid experiment at Mt. Chacaltaya are studied in detail and compared with those of simulations taking into accounts the specific detection bias of the experiment. It is shown that the observed characteristics of the atmospheric families accompanied by large air showers, Ne > 10^7, and also those of air-showers accompanying families can not be explained simply by increase of heavy nucleus in primary cosmic-rays. Discussions are also given on the comparison with the results of the other hybrid experiments on high mountains.

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 4 (HE part 1), pages 23-26